Production of lubricating oil



Dec. 16, 1952 c. M. VAN BATTUM 2,622,112

PRODUCTION OF LUBRICATING OIL Filed Oct. 9, 1950 IALKYLATmN ALKYLHUON I ALKYLATE I I'ALKYLATE l BLENDWC'I TANK To LUBRmATme on.

Patented Dec. 16, 1952 UNITED STATES PATENT OFFICE PRODUCTION OF LUBRICATTN G OIL Application ,Qctober 9, 1950, Serial No. 189,291- In the Netherlands October 13, 1949 TCIaims. .1

This invention relates to the production of hydrocarbons useful as lubricating oils by thealkylation of aromatic hydrocarbons with olefins. It deals with an improved method of alkylation utilizing mixtures of aromatic hydrocarbons .and olefinic mixtures to more efiicientlyproduce high yields of lubricating oils having a combination of desirable properties.

It has been proposed (see, for example, British Patent 316,274) to produce viscous oils from ,aromatic hydrocarbon mixtures obtained by extracting mineral oil with liquid sulfur dioxide by reacting the extract with lower olefins :such as ethylene and propylene in the presence of a Friedel-Crafts catalyst. It has also been suggested in British Patent 557,177 to prepare a pour point depressant for waxy lubricating oils by reacting an aromatic compound, preferably a polynuclear aromatic compound, such as naphthalane, with an olefin or a mixture of olefins with to 9 carbon atoms, in the presence ofa Friedel- Crafts catalyst, and by distilling off from the reaction product the components which boil below approximately 315 C.

Such methods of operation are not suitable for efiicient production of lubricating oil when starting with mixtures of aromatic hydrocarbons of the kerosene boiling range and mixtures of 8 to 18 carbon atoms per molecule such as are obtained by cracking higher paraffin hydrocarbons. It has been found that with these readily available starting materials the yield of lubricating oil of satisfactory properties is prohibitively low. Thus, in experiments carried out by alkylating aromatic extracts prepared from kerosene and having a boiling range of from 140 C.-160 C. to 260 C.280 C., in the presence of an aluminum chloride ,alkylation catalyst, with a mixture of olefins of '8 to '18 carbon atoms from the vapor phase cracking of paraflin wax, it was found that the products obtained after distilling ofi the unconverted components havethe viscosity of a spindle oil but do not meet other speciflcations, particularly the flash point requirements, and are therefore not suitable for practical purposes. The Manufacturing Pool Speciflcations published in Great Britain, for instance, require a, flash'point (determined according to the Pensky-Martens closed cup method) of .at least 201 C. for a lubricatingoil withanEngler ,a lubricating oil with a sufficiently :high flash point it would be necessary to remove such a large quantity of "the more volatile? components from the alkylation-producti that the yield of lubricating oil giving satisfaction in.-practice would be prohibitively low. Moreover; only high: viscosity lubricating oils would be obtained inthis It is an object of'the present inventio to-provide a method whereby high yields'rofliibricating oils having a satisfactory combination of properties, particularly desirable viscosity, viscosity index, flash point, pour point, stabilityand lubricating properties, can be obtained from mixtures of aromatic hydrocarbons of the ikerosene boiling range and olefim'c fractions having'8 to 18- carbon atoms per molecule.

from the following disclosure in which the use of aromatic extracts of kerosene will be emphasized as a particularly advantageous source of the aromatic hydrocarbon mixtures used as starting material, although it will be understood that analogous mixtures of aromatic hydrocarbons obtained in other'ways canbe similarly employed in the new process.

According to the present invention lubricating oil with a desirable combination of properties, particularly a high viscosity index and a satisfactory combination of viscosity and high flash point, is prepared from mixtures of aromatic hydrocarbons boiling in the range of between C. and 280 C. such, for example, as "those obtained by selective extraction of kerosene with solvents having a preferential solubility for aromatic hydrocarbons in the presence of parafiins, on theone hand, and mixtures of predominantly ,straight chain mono-olefins of '8 to 18 carbon atoms per molecule, on the other hand,iby divid- Other objects and advantages of the invention will be apparenting both the aromatic mixture and the olefinic mixture each separately as by distillation, for instance, into a lower boiling fraction and a higher boiling fraction, alkylating the lower boiling part of the aromatic extract with the higher boiling part of the mixture of olcfins, alkylating the higher boiling part of the aromatic extract with the lower boiling part of the mixture of olefins, and mixing the alkylation products thus obtained. By mixing the two alkylation products in different proportions, this process makes it moreover possible to prepare lubricating oils of divergent viscosities, varying from about E5u=6 to about E5o=18, having high viscosity indexes in combination with other desirable properties. These steps of the invention are shown in the flow sheet of the new process appearing in the accompanying drawing where only major operations are illustrated, and it will be understood that the schematic representations of the various steps are not intended to preclude ancillary or other operations.

The alkylation of the lower boiling fraction of the aromatic extract with the higher boiling fraction of the olefins is preferably carried out with a high molar ratio of aromatics to olefins. At least 2 mols, and preferably 2.5 to 3 mols, of aromatic compounds per mol of olefins should be present. Considerably larger quantities of the aromatic extract per mol of olefins can be applied, for example, mols of aromatic compounds or more per mol of olefins. The preferred molecular ratio of 2.5:1 to 3:1 corresponds approximately to a weight ratio of aromatics to olefins of 1.6:1 to 2:1. The alkylation of the lower boiling fraction of the aromatic extract with the higher boiling fraction of the olefins produces a thin lubricating oil with a viscosity index of 95 to 110 and a sufficiently high flash point (above 200 C.)

In alkylating the higher boiling fraction of the aromatic extract with the lower boiling fraction of the olefins, preferably at least 2 mols of the latter are applied per mol of aromatic compounds. Usually 2 to 3, and most preferably about 2.5 mols of olefins are employed per mol of arcmatic compounds. The molecular ratio of 2.521 corresponds approximately to a Weight ratio of olefins to aromatic compounds of 3:1. The alkylation of the higher boiling fraction of the arcmatic extract with the lower boiling fraction of the olefins produces a thick lubricating oil with a viscosity index of 95 to 105 and a sufficiently high flash point. If desired, the viscosity of this alkylation product can be further increased by distilling off the lighter components.

The point of division into higher boiling and lower boiling fractions of both the mixture of olefins and the aromatic extract can be varied considerably depending upon the particular type of lubricating oil which is desired. Thus, in the case of the olefin mixture, the splitting may be effected at any of the olefins with 11 to 17 carbon atoms. For the aromatic extract, the splitting into the lower and the higher boiling fractions can be carried out at any boiling point between 200 C. and 245 C. at atmospheric pressure. The splitting of the aromatic extract and of the starting mixture of olefins is advantageously carried out by distillation to these desired splitting points.

The aromatic extracts can be prepared by extracting the aromatic compounds from kerosene with a selective solvent. Liquid sulfur dioxide is particularly suitable as a selective solvent. However, other selective solvents for aromatic hydrocarbons in the presence of parafiins, such as furfural, nitrobenzene or antimony trichloride, can also be applied successfully. After extraction, the extract is separated from the residue and the selective solvent is removed from the extract. By distilling the extract thus obtained a fraction with an initial boiling point of 140 C.-l60 C. and a final boiling point of 260 C.-280 C. can be isolated as the starting material for the new process. However, if desired, the extraction with a selective solvent can be replaced by other separation methods to concentrate the aromatic compounds from kerosene, for example, a percolation over silica gel of a kerosene diluted with a light hydrocarbon oil, such as pentane, whereafter the aromatic compounds adsorbed thereon are dissolved in a volatile solvent, such as pentane, which is finally distilled ofi. Still other methods of producing such starting mixtures of aromatic hydrocarbons boiling in the kerosene range can likewise be used.

It should be noted that not every kerosene which, on the ground of the ring analysis, has a high content of aromatic compounds forms a suitable initial material for the preparation of the alkylation products according to the invention. The aromatic compounds contained in the kerosene, or at least the greater part of them, must be alkylatable, i. e. must have a replaceable hydrogen atom attached to a nuclear carbon atom of the aromatic ring.

Suitable mixtures of olefins with 8 to 18 carbon atoms are, for example, those obtained by the cracking of heavy paraffin hydrocarbons, most preferably by cracking paraifin which is solid at room temperature in the gas phase and by distilling the C8-C13 fraction out of the cracked product. It may be advisable to remove at least the majority of the very reactive components, such as di-olefins, from the cracked product before distilling 01f the Cs-Cis fraction by, for instance, bringing the cracked product into contact with a small proportion, for example 0.5% by weight, of aluminum chloride, preferably at a moderately elevated temperature, for example 60 C. to C., which will cause these very reactive components to polymerize. After the aluminum chloride and any sludge formed have been removed, the Cs-Cis fraction is recovered from the product by distillation. Other methods of removing the undesired highly reactive components, if present, may also be used.

strongly branched olefins, such as the polymer olefins obtained by the polymerization of lower olefins, are not suitable for the purpose of the invention in which, most preferably, Caz-C18 mixtures of predominantly straight chain alpha olefins are used as the starting material.

Of the two starting materials used, namely, aromatic extract and olefin mixture, the olefin mixture is usually the more expensive; consequently, it is generally desirable to adapt the consumption of the aromatic extract to that of the olefins so that the latter are consumed as completely as possible.

The two fractions of the aromatic extract are alkylated with the different fractions of the olefin mixture in the presence of an alkylation catalyst which may be the same or different in the two reactions. All the known Friedel-Crafts metal halide catalysts are efiective for these alkylations, and aluminum chloride is particularly suitable. Aluminum halides can be used as the anhydrous solid or in the form of complexes or double salts or solutions in suitable solvents. Organic complexes of active metal halides with hydrocarbons are suitable and the complexes or sludges formed in the course of the reaction can, preferably after addition of fresh metal halide, be used as the catalyst. Other examples of suitable catalysts are, for instance, hydrogen fluoride, boron trifluoride, sulfuric acid, ferric chloride, and zinc chloride. The amount of catalyst which it will be desirable to use will vary depending upon the activity of the particular catalyst or catalyst mixture chosen. When using aluminum chloride, for example, as the catalyst, a quantity of about 0.5% to about by weight thereof, based upon the total amount of reaction mixture present, is satisfactory. Most preferably, the proportion of aluminum chloride applied is 1% to 4% by weight for the alkylation of the lighter fraction of the aromatic extract with the heavier fraction of the olefins, and 4% to 6% by weight for the alkylation of the heavier fraction of the aromatic extract with the lighter fraction of the olefins.

The alkylation of the lighter fraction of the aromatic extract with the heavier fraction of the olefins can take place at temperatures varying from about 20 C. to about 100 C. and is preferably carried out at temperatures between about 20 C. and 70 C. The alkylation of the heavier fraction of the aromatic extract with the lighter fraction of the mixture of olefins can generally take place at temperatures from about 10 C. to about +100 C. and, generally, reaction temperatures of +10 C. to +50 C. are preferable.

The duration of the alkylation reactions is dependent on the temperature applied and the proportion and nature of the catalyst. If aluminum chloride is applied as catalyst and this catalyst is added gradually, the reaction time is usually from 3 to 8 hours. After completion of the reaction, the two alkylation products are worked up by first removing any bottom layer of catalyst sludge and higher molecular products. This can, for instance, be done by simply decanting or pumping off the top layer containing the alkylation product, or by separating the layers with the aid of a separatory funnel or by centrifugation.

The upper layer can then be treated with an alkaline substance, for instance, lime, to remove any acid components present. To improve the color of the alkylation product and to remove any chlorine content caused by the catalyst, the product can be treated with bleaching earth. The two treatments can be combined by heating the alkylation product with a mixture of bleaching earth and lime. A suitable heat treatment is, for example, the heating for to 2 hours at a temperature between 150 C. and 240 C., preferably between 200 C. and 240 C. To prevent oxidation of the reaction product during this treatment, it can take place in an inert atmosphere, for example, an atmosphere of nitrogen. It is also possible to conduct nitrogen or another inert gas through the reaction product, which, at the same time, causes thorough stirring. After the treatment with lime and bleaching earth these substances are removed by filtration.

The filtrate can finally be subjected to a vacuum distillation to remove non-converted components of the initial materials. The recovered unreacted starting materials can be recycled for further reaction. The alkylates obtained as a result of the two alkylation reactions are finally mixed in the ratio which is necessary to obtain the lubricating oil of the desired viscosity.

6 In this way it is possible to prepare lubricating oils with any viscosity between E5o== 6 and Est-=18, a viscosity index of approximately 100, and a flash point above 200 C.

The following examples illustrate suitable methods of carrying out the new process when using a kerosene extract having a boiling range of 160 C. to 260 C. with a mixture of olefins of 8 to 18 carbon atoms, and show its advantages over direct alkylation of the extract with the olefin mixture.

The aromatic extract used was obtained from kerosene by extraction with liquid sulfur dioxide, and the mixture of olefins of 8 to 18 carbon atoms was produced by cracking a residual, oil-containing parafiin wax in the vapor phase, treatin the cracked product for 3 hours at 80 C. with 0.5% by weight of aluminum chloride to remove the most reactive components, such as di-olefins, and isolating the Cs-Cra fraction by vacuum distillation from the cracked product, after removing the catalyst and the sludge formed.

The kerosene extract was separated into two fractions by distillation to form a fraction with a boiling range of 160 C. to 210 C. and a fraction boiling 210 C. to 260 C. The mixture of olefins was divided into two fractions in each of four different distillations, which in each case split the mixture into a fraction with a chain length of C3-Cn and a fraction with a chain length of Cn+l-Cl8, whereby n was ll, l3, l5, and l! successively. In all the experiments the two olefin fractions were used in the same ratio as that in which they were present in the entire C8-C18 mixture, while two parts by weight of the lighter fraction of the kerosene extract were reacted with one part by weight of the Cn+1-Cl8 olefins and one part by weight of the heavier fraction of the kerosene extract was reacted with three parts by weight of the C8-C1; olefins.

Eight alkylations were carried out in pairs in which the lower boiling fraction of the aromatic extract was reacted with a higher boiling fraction of the olefin mixture and the corresponding lower boiling fraction of the olefin mixture was reacted with the higher boiling fraction of the aromatic extract. Each alkylation was carried out in a stirred autoclave at 45 C. using 3.6% by weight of aluminum chloride based on the total weight of the reaction mixture and a total reaction time of about 4 to 5 hours.

At the end of the reaction two layers had formed in the reaction mixture. The bottom layer, consisting of catalyst sludge, was removed. The upper layer was treated with 10 parts by weight of an aqueous sodium hydroxide solution of 20% concentration and washed with water after the aqueous alkali layer has been removed.

The oils obtained by alkylating the fraction of the kerosene extract having a boiling range of 160 C.-210 C. with the Cn+l-C18 olefins were distilled off to a viscosity of E5o=ap-prox. 4, so as to remove non-converted components of the initial mixture; the oils thus obtained had a flash point higher than 200 C. and a viscosity index between and 110.

The products obtained by 'alkylating the fraction of the kerosene extract having a boiling range of 210 C.260 C. with the Ca-Cn olefins were distilled off after the completion of the alkylation reaction to a viscosity of E5o=25, so as to remove lighter components (including nonconverted components 'of the initial mixture). The oils thus obtained had flash points of 7 2 30 C.-240 0.. and a viscosity index between. 95 andl 05.' ...i l 7 The parts by weight of olenfisbrought into reaction and the parts by weight of lubricatingoil obtained therefrom as .well as the flash points of the mixtures finally obtained were for the different values of n as follows:

In the'third column of this table the quantities of lubricating oil obtained in each of the two alkylation reactions are indicated separately, while the fourth column shows the total quantity of lubricating oil obtained by mixing these quantities. The fifth column shows the viscosities expressed in degrees Engler at 50 C. of the products obtained after this mixing, while finally the sixth column shows the flash points of these mixtures. The viscosity index of each of these mixtures was approximately 100.

When the same starting aromatic extract of boiling range 160 C.-260 C. without fractionation was reacted with the same starting mixture of olefins of 8 to 18 carbon atoms, also unfractionated, in the proportions of 30 parts of extract to 70 parts of olefin mixture by weight, under the same conditions, the finished product recovered in the same way failed to meet the specifications for a satisfactory lubricating oil, particularly in respect to proper relationship of flash point and viscosity. In an effort to improve the product, it was distilled to remove a part, and the flash point and viscosity of the residue were again determined. The properties of the residue being still unsatisfactory, further distillations were carried out with the following results:

Yield, wt. k percent of (Pensk Visc., Visc., Product the original 37 0., 99 0., E50

miritirlesof closed in c. s. in c. s.

0. Original final 8 produce less deposits in engines than do each of the components individually.

These tests were carried out with lubricating oils prepared as follows:

A fraction .of an aromatic extract of kerosene boiling from 160 C. to 210 C. was alkylated with a Cir-C18 fraction of cracked wax olefins in the ratio of two parts by weight of the aromatic extract fraction to one part by weight of the olefin fraction, The .alkylation product was distilled off to obtain a light component having a viscosity of E5o=4. The higher boiling fraction of the aromatic extract, boiling range 210 C.-26'0 C., was .alkylated with the C8-C13 fraction of the olefins in the ratio of one part by weight of aromatic fraction to three parts by weight of the olefins, and the alkylation product distilled off to obtain a heavy component having a viscosity of E50=25.

Three engine tests were now carried out, using as lubricating oil (1) the light component, (2) the heavy component, and (3) a mixture of the light and the heavy components. In the first test, using only the light component as lubricating oil, the lighter components of the oil were first distilled off to obtain a residue having a viscosity of E50=l4 to make the viscosity properties of the lubricating oil better comparable with those of the heavy component and. the mixture of light and heavy components. The mixture of light and heavy components was a mixture of 20 parts by weight of the light component with a viscosity of E5o=4 and parts by weight of the heavy component (1350:25), which mixture had a viscosity of E50=18.

The tests were carried out in a stationary single cylinder Deutz gasoline engine under full load mm. bore, stroke mm). The engine was operated under the following conditions:

Cooling temperature (glycol as cooling liquid) C. Oil temperature C. 80 Engine speed R. P. M. 1200 The tests were of 40 hours duration and the following results were obtained:

- Mixture of D 1 fi fi Heavy Light and GP 0S1 n g Component Heavy component Components 1st piston-ring groove. m'.- 109 48 24 2nd piston-ring groove. .mg 12 35 0 Remaining piston-ring grooves mg 5 20 0 Inside the piston mg 222 0 0 It will thus be seen that the new process of the invention offers many advantages over prior methods of synthesizing lubricating oils and that the process is capable of considerable variation, not only in regard to the starting materials which may be used but also in respect to the methods of operation which may be adopted. Thus, while pure or relatively pure mixtures of alkylatable aromatic hydrocarbons of the kerosene boiling fractions with the split point between 200 C. and 245 C., separately alkylate these fractions with higher and lower boiling fractions of olefins as previously described, and separate from the alkylation products by distillation the nonaromatic components of the kerosene fractions which have not taken part in the alkylation before blending the alkylates to obtain the desired lubricating oil of high quality. The alkylations may be carried on continuously, intermittently or batchwise. The new products of the invention may be employed with any of the known lubricating oil additives such, for instance, as anti-oxidants, or with other lubricants or the like, although their advantageous combination of properties make them also useful without the addition of other components. Still other variations may be made in the process which is not limited by the examples given by way of illustration nor by any theory proposed in explanation of the improved results which are obtained.

I claim as my invention:

1. A method of producing aromatic hydrocarbons useful as lubricating oil from a mixture of aromatic hydrocarbons boiling in the kerosene range and a mixture of predominantly straight chain olefins having 8 to 18 carbon atoms per molecule, which comprises separating said aromatic mixture into two fractions, one of which boils higher than the other, separating said olefin mixture into a lower boiling fraction and a higher boiling fraction, alkylating said higher boiling fraction of the aromatic mixture with the lower boiling fraction of said olefin mixture, alkylating the lower boiling fraction of the aromatic mixture with said higher boiling fraction of the olefin mixture, and blending alkylation products of the two said alkylations.

2. A method of producing aromatic hydrocarbons useful as lubricating oil from a mixture of aromatic hydrocarbons having an initial boiling point within the range of from 140 C. to 160 C. and a final boiling point within the range of from 260 C. to 280 C. and a mixture of olefins of 8 to 18 carbon atoms per molecule obtained by cracking higher paraffin hydrocarbons, which comprises distilling said mixture of aromatic hydrocarbons to separate two fractions, the lower boiling of which has an upper boiling limit between 200 C. and 245 C. at atmospheric pressure and the higher boiling fraction of which is the remainder of said aromatic mixture, dividing said mixture of olefins into a C3-C1 fraction and a Cn+1-C18 fraction, where 'n is a number from 11 to 17, alkylating said higher boiling fraction of the aromatic mixture with the C8Cn fraction of the olefin mixture, alkylating the lower boiling fraction of the aromatic mixture with the Cn+1c18 fraction of olefins, and blending alkylation products therefrom to form a lubricating oil having a viscosity of Eso=6 to Eo=18.

3. A method of producing aromatic hydrocarbons useful as lubricating oil from a mixture of aromatic hydrocarbons having an initial boiling point within the range of from 140 C. to 160 C. and a final boiling point within the range of from 260 C. to 230 C. and a mixture of predominantly straight chain olefins having 8 to 18 carbon atoms per molecule, which comprises separating said aromatic mixture into two fractions, the lower boiling of which boils in the range of 140 C. to 245 C. and has a final boiling point within the range of from 200 C. to 245 C". and the higher boiling of which boils in the range of 200 C. to 280 C. and has an initial boiling point within the range of from 200 C. to 245 C., dividing said mixture of olefins into a oil-C11. fraction and a Cn+1-C18 fraction, where n is a number from 11 to 1'7, reacting a mixture of said lower boiling aromatic fraction and said C1L+1C18 fraction of olefins containing at least two mols of aromatic hydrocarbons per mol of olefin under alkylating conditions in the presence of an alklation catalyst, reacting said higher boiling fraction of the aromatic mixture with said Gil-Ch fraction of olefins in a ratio of at least two mols of olefin per mol of aromatic hydrocarbon present under alkylating conditions in the presence of an alkylation catalyst, and blending alklation products therefrom to form a lubricating oil having a viscosity of E50=6 to E50=18.

4. A method of producing aromatic hydrocarbons useful as lubricating oil from a mixture of aromatic hydrocarbons boiling in the kerosene range and a mixture of predominantly straight chain olefins having 8 to 18 carbon atoms per molecule, which comprises separating said aromatic mixture into two fractions, one of which boils higher than the other, separating said olefin mixture into a lower boiling fraction and a higher boiling fraction, alkylating said higher boiling fraction of the aromatic mixture by reaction with the lower boiling fraction of said olefins in the ratio of 2 to 3 mols of olefins per mol of aromatic hydrocarbon, at a temperature of 10 C. to 50 C. in the presence of 4% to 6% by weight of aluminium chloride based upon the weight of reaction mixture, alkylating the lower boiling fraction of said aromatic mixture with the higher boiling fraction of said olefins in the ratio of 2.5 to 3 mols of aromatic hydrocarbon per mol of olefin, at a temperature of 20 C. to C. in the presence of 1% to 4% of aluminum chloride based on the weight of the reaction mixture, and blending alkylation products of the two reactions.

5. A process according to claim 4 wherein the mixture of aromatic hydrocarbons is a liquid sulfur dioxide extract of kerosene.

6. A method of producing aromatic hydrocarbons useful as lubricating oil from a mixture of aromatic hydrocarbons having an initial boiling point within the range of from C. to C. and a final boiling point within the range of from 260 C. to 280 C. and a mixture of olefins of 8 to 18 carbon atoms per molecule obtained by cracking higher paraifin hydrocarbons, which comprises distilling said mixture of aromatic hydrocarbons to separate two fractions, the lower boiling of which has an upper boiling limit between 200 C. and 245 C. at atmospheric pressure and the higher boiling fraction of which is the remainder of said aromatic mixture, dividing said mixture of olefins into a C8-C1; fraction and a Cn+1-C18 fraction, where n is a number from 11 to 1'7, alkylating said higher boiling fraction of the aromatic mixture with the C8-Cn fraction of olefins in the ratio of 2 to 3 mols of olefins per mol of aromatic hydrocarbon, at a temperature of l0 C. to 50 C. in the presence of 4% to 6% by weight of aluminum chloride based upon the weight of reaction mixture, alkylating the lower boiling fraction of said aromatic mixture with the Cn+l-C18 fraction of olefins in the ratio of 2.5 to 3 mols of aromatic hydrocarbons per mol of olefin at a temperature of 20 C. to 70 C. in the presence of 1% to 4% of aluminum chloride based on the weight of reaction mixture, and blending alkylation 11 products therefrom to form a lubricating oil hav- UNITED STATES PATENTS ing a viscosity of E5o=6 to E5o=18. Number Name Date '7. A process according to claim 6 wherein the 2,071 521 Hartmann et aL Feb 23 1937 more reactive components of the cracking product 2 232118 Kyrides 1941 are removed by selective polymerization with a 5 2360'446 Reid I 1944 small amount of aluminum chloride before carry- 2518529 De Casson et Aug 1950 ing out said alkylations.

CAREL VAN BATTUM- OTHER REFERENCES REFERENCES CITED 10 Hall, Research on Synthetic Lubricants, Oil

The following references are of record in the ggg g' Jour' (Mar' 1935) 96 (3 file of this patent: 

1. A METHOD OF PRODUCING AROMATIC HYDROCARBONS USEFUL A LUBRICATING OIL FROM A MIXTURE OF AROMATIC HYDROCARBONS BOILING IN THE KEROSENE RANGE AND A MIXTURE OF PREDOMINANTLY STRAIGHT CHAIN OLEFINS HAVING 8 TO 18 CARBON ATOMS PER MOLECULE, WHICH COMPRISES SEPARATING SAID AROMATIC MIXTURE INTO TWO FRACTIONS, ONE OF WHICH BOILS HIGHER THAN THE OTHER, SEPARATING SAID OLEFIN MIXTURE INTO A LOWER BOILING FRACTION AND A HIGHER BOILING FRACTION, ALKYLATING SAID HIGHER BOILING FRACTION OF THE AROMATIC MIXTURE WITH THE LOWER BOILING FRACTION OF SAID OLEFIN MIXTURE, ALKYLATING THE LOWER BOILING FRACTION OF THE AROMATIC MIXTURE WITH SAID HIGHER BOILING FRACTION OF THE OLEFIN MIXTURE, SAID BLENDING ALKYLATION PRODUCTS OF THE TWO SAID ALKLATIONS. 